Simplify ( x² - 36/4x - 4 ÷ x² + 12x + 36/x² + 5x - 6 ):
a. ( (x - 6)(x + 6)/4(x - 1) )
b. ( (x - 6)(x + 6)/(x - 1)(x + 6) )
c. ( (x - 6)(x + 6)/(x - 1)(x + 3) )
d. ( (x - 6)(x + 6)/4(x + 1) )